The process well known under the registered trade mark “SMART CUT®” is a widely used transfer technique, which generally consists of implanting a dose of atomic or ionic species in a donor substrate, to create therein an embrittlement zone at a determined depth, delimiting a thin layer to be transferred, adhering the donor substrate on a support substrate or receiver substrate and prompting fracturing of the donor substrate at the level of the embrittlement zone, causing the detachment of the thin layer adhering to the receiver substrate.
Such a process is generally satisfactory, yet it does require high doses of atomic species, with inevitable repercussions on the overall cost of execution.
There is still a need, therefore, to employ another process for treating a piece or a substrate, which finally detaches thin layers or thick layers of a substrate, efficiently, cleanly and using a process that is easy to execute.
Also, the article “Laser heating of thick layers through the backwards, self-sustained propagation of a steep and steady state thermal front,” by Monsieur Michel Bruel (2009), as well as French Patent Application Serial No. 07 57986, describe an at least local heating process of a plate comprising at least one layer to be heated and a sub-layer.
In these documents, the sub-layer has the particular feature of being absorbent vis-à-vis a luminous flux of predetermined wavelength, this absorption occurring independently of temperature conditions.
Also, the layer to be heated has, as such, the particular feature of having a coefficient of absorption of the luminous flux, which is low at ambient temperature and increases as this temperature rises.
If this layer to be heated is irradiated by means of the luminous radiation, the absorbent sub-layer can then be heated by passing through the layer to be heated, which is to some degree transparent to a light beam.
In this way, the interface, which separates the layer to be heated, and the sub-layer is heated and then heats the layers that are adjacent to it, which will, in turn, make them absorbent, such that the layers most distant from the absorbent layer will gradually become more and more absorbent.
This produces a “thermal front” that progresses quickly, very homogeneously and substantially adiabatically.
This technique, therefore, rapidly heats localized regions of a substrate to considerable depths, which would be heated improperly only if a thermal treatment was undertaken where the sole intervening mechanism would be thermal diffusion, and at the end of a particularly long heating period.
It was realized that it was possible to make use of such a technique to treat such a substrate so as to embrittle it. In some circumstances, this embrittlement could cause detachment of a layer of interest.
The thickness of such a layer, by way of non-limiting example as per the relevant application, can typically be in the range of 0.5-50 micrometers.